1. Field of the Invention
This invention relates to polyamides. In one aspect, the invention relates to a process for manufacturing polyamides from .alpha.,.omega.-diamine and an .alpha.,.omega.-diamide while in another aspect, the invention relates to a process utilizing an oxygenated compound of carbon, boron, nitrogen or sulfur as a catalyst. In still another aspect, the invention relates to an improved process for manufacturing nylon-6,6 from hexamethylenediamine and adipamide utilizing a catalyst system composed of an oxygenated compound of carbon, boron, nitrogen or sulfur.
2. Description of the Prior Art
It is known in the art that commercially available nylons may be prepared by polymerization of various monomers and combinations of monomers. For example, various nylons may be prepared from the polymerization of diamines with dicarboxylic acids, the polymerization of dinitriles with diamines in the presence of water, the polymerization of aminonitriles in the presence of water, or the polymerization of lactams.
In part, the instant invention deals with nylons resulting from the polymerization from diamines and diamides. Very few references suggest the polymerization of these two monomer types. For example. U.S. Pat. No. 3,900,450 teaches a process for polymerizing amino acids, diamines, dibasic carboxylic acids and other amide forming derivatives in which diamides are specifically included.
Recently, Curatolo et al., U.S. application Ser. No. 677,262 disclosed a catalytic process for the manufacture of polyamides from diamines and diamides using an oxygenated phosphorus compound, such as the alkali metal salts of phosphoric acid, as a catalyst. These oxygenated phosphorus compounds sometimes yielded poor thermal stability in the resulting polyamide. An advantage to the catalysts of the instant invention is that they provide good thermal stability for polyamides produced by the polymerization of diamines and diamides.
Lastly, the instant invention relates to the production of nylon-6,6 from hexamethylenediamine and adipamide. Commercially, nylon-6,6 is produced from hexamethylenediamine and adipic acid. The present invention offers an alternative to the adipic acid route in preparing this most useful polymer.